1. Field of the Invention
The present invention relates to radio-electronics and, more specifically, to antennas for radio transceivers.
2. Description of the Related Art
With the continuing development of wireless communication systems, conventional wire-line transmissions are gradually yielding to or being supplemented by wireless transmissions. Many portable electronic data processors, such as laptop computers and personal digital assistants, are now using wireless communication methods to transmit and receive data. In addition, there has been a marked increase in the use of cellular and cordless phones.
One general problem in the design of a portable wireless communication device is associated with its antenna. When an external dipole or monopole structure is used as an antenna, it can typically be easily broken during normal use. Also, the cost of incorporating an external antenna and its conduits into the device can add considerably to the cost of the final product. For at least some of these reasons, wireless equipment manufacturers often use planar (e.g., patch) antennas instead of or in addition to external antennas.
A conventional patch antenna is often manufactured by forming a conducting ground plane at one side of a printed circuit board and a conducting patch at the other side of the board. However, one problem with this antenna structure is that it has a relatively narrow bandwidth due to its highly resonant characteristics. Unfortunately, known methods for increasing the bandwidth of a patch antenna without increasing its size are relatively complicated and/or generally not conducive to use in mass production.